System and method of control for electric motors.



N. W. STORER.

SYSTEM AND METHOD OF CONTROL FOR ELECTRIC MOTORS.

APPLICATION FILED OCT-5. 1912.

1,155,170. Patented Sept; 28, 1915.

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N. W. STORER. SYSTEM AND METHOD OF CONTROL FOR ELECTRIC MOTORS.APPLICATION FILED OCT. 5, 1912. 1,155,170. Patented Sept. 28, 1915.

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were PATENT OFFICE.

NORMAN-W. sronnn orfrrrrsnonen, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSEELECTRIC AND MANUFACTURING COMPANY, A CORPORATION or PENNSYLVANIA.

SYSTEM AND METHOD OF CONTROL FOR ELECTRIC MOTORS.

Specification of Letters Patent.

Patented sept. 28, 1915.

Application filed October 5, 1912. Serial No. 724,067.

To all whom it may concern lie it known that I, NORMAN WV. S'ronnn, acitizen of the United States, and a resident of Pittsburgh, in thecounty of Allegheny and State of Pennsylvania, have invented a new anduseful- Improvement in Systems and Methods of Control for ElectricMotors, of which the following is a specification.

My invention relates to systems and methods of control for electricmotors, and it has special reference to the-control of electric vehicleor automobile motors which are supplied with energy from storagebatteries.

The object of my invention is to provide a system and method of controlfor an electric motor of the character indicated, wherebya plurality ofmotor-operating speeds and also a series of regenerative braking speedsmay be secured for retarding the motor, the arrangement beingsuch thatall portions of the battery will. charge and discharge substantiallyuniformly. I

In my previous Patent No.- 765,209, granted JulylS), 190tto theIVestinghouse Electric & Mfg; Company, there is setforth a method ofcontrol of the general character above indicated which consists invarying the voltage applied to the motor by changing the connections ofthe battery from series to multiple groups, and field magnet windings ofthe motor from series to multiple sections. A .i

According to my present invention, I provide a relatively highspeedmotor-operating connection in addition to the -motor-operatingconnections set forth in the above-named patent, and, furthermore, Iprovide'a series of regenerative braking positions in which theexcitation of the field magnet windings is. gradually increased and thecircuit con nections are such that energy is generated underadvantageous conditions for charging the storage battery.

In my co-pending application, Serial: No.

124,068, filed of even date herewith, I have set forth a control systeminwhich automatic means are provided for adjusting and regulating thefield excitation or a motor during the braking period in order to returnenergy to :the: supply :of: the-system;

My present invention has some features in common with the applicationreferred to, but a series of control positions is provided whereby thedesired field regulation may be obtained manually with relatively smallexpense when a storage battery constitutes the source of energy andwhere it would be impracticable to employ an automatic system ofregulation. 7

Figure 1 of the accompanying drawings is a diagrammatic view of a systemof control embodying my invention, a controller of the drum type beingshown developed into a single plane in a well known manner. Figs. 2 to7, inclusive, are diagrams respectively illustrating the circuitconnections for the six accelerating or motor-operating positions of thecontroller, and Figs. 8, 9 and 10 are similar diagrams illustrating thecircuit connections for the three braking positions of the controller.Fig. 11 is a diagrammatic view, corresponding to Fig. 1, of a systemwhich embodies a modification of my invention,and Figs. 12 to 17,inclusive, are simple diagrams illustrating the circuit connections forthe various positions of the controller of Fig. 11.

-Referring to Figs. 1 to 10, inclusive, of the drawings, the controlsystem here shown comprises an electric motor having an armature 1 andfield magnet windings 2 and 3, a

reversing switch 4-, a controller 5 adapted to occupy a plurality ofmotor-operating po sitions a-to f, inclusive, and a plurality of brakingpositions x, y and 2, storage batteries 6 and 7, a battery chargingswitch 8 and a charging plug 9. The battery charging switch 8 is atriple pole, doublethrow switch and, when thrown in one direction,connects the storage batteries 5. and 7 in series relation between theterminals of the charging plug. When thrown in the opposite position,the connections 01 the storage batteries are dependent upon. thepositions of the controller 5, as hereinafterpointedout.

Assuming that the reversing switch 4 is moved into a position is andthat the con troller Sis moved intoitsposition a, a connectionisestablished from one terminal 10 ot'the'battery G-througlra switch.blade 11, acondnctor 12 and control finger 13, to a contact member 14. Aconnection is also established from a terminal 15 of the battery 7through a switch blade 16, a conductor 17 and a contact finger 18 to thecontact member 14, circuit being continued from this point to a contactfinger 19, a conductor 20, the field magnet winding 2, a conductor 21,contact fingers 22 and 23, which are bridged by a contact member 24, aconductor 25, the field magnet winding 3, a conductor 26, contactfingers 27 and 28, which are bridged by a contact member 29, a conductor30, contact fingers 31 and 32, which are bridged by a contact member 33of the reverser, the motor armature 1, a conductor 34, contact fingers35 and 36, which are bridged by a contact member 37, a conductor 38, aresister 39, contact fingers and 41, which are bridged by contact member42, a conductor 43, a switch blade 44, and a conductor to a terminal 46ct -the battery 7. A connection is also established from the contactmember 42 through a finger 47 and a conductor 48 to a terminal 49 of thebattery 6. Circuit connections are thus established as shown in Fig. 2of the drawings.

If the controller is now moved to position Z), a contact finger 50 willengage the contact member 42. The resistor 39 will thus be '1 shortcircuited., the connections being as shown in Fig. 3.

If the controller is moved to position 0, the terminals 10 and 15 of thestorage batteries are still connected to the contact mem ber 14, circuitbeing continued from this point through the finger 19, the conductor 20,the field magnet winding 2, a conductor 21, and the contact finger 22 tothe contact member 29. The contact finger 23 also engages the contactmember 14, and, consequently, the field magnet winding 3 is con nectedto the contact members 14 and 29 in parallel relation with the fieldmagnet winding 2. The circuit connections are otherwise the same asbefore, and, consequently, the arrangement of Fig. 4 is obtained.

In position (Z of the controller, the field magnet windings 2 and 3 arerestored to their series relation as in positions a and b but thestorage batteries are changed from a multiple to a series relation sincecontact fingers 18 and 47 become respectively disengaged from thecontact members 14 and 42 and are interconnected by a contact member 51.(See Fig. 5).

In position 6, the field magnet windings 2 and 3 are again connected inmultiple circuit relation, the batteries being still connected inseries. (See Fig. 6).

In position 7, the field magnet windings are again connected in seriesrelation but a cross connection is established from an intermediatepoint 52 in the storage battery 6 through a conductor 53 and a contactfinger which now engages a contact member 60,

continues through a conductor 61 to a contact member 29 to one terminalof the motor armature, the connection being such as to throw a portion55 of the storage battery 6 directly across the field magnet windings 2and 3 as shown in Fig. 7.

It thus appears that a plurality of gradually-increasing motor speedsare provided by first establishing a low-voltage connection between thebatteries, a strong field and including a resistance in the armaturecircuit. The armature resistance is then excluded, the field weakened byconnecting its parts in multiple relation, a high-voltage connectionestablished by connecting the batteries in series, first with a strongfield, then with a weaker field, and finally establishing an armaturecircuit through the interconnection provided by the conductor 53independent of the field magnet windings, thereby materially weakeningthe field strength.

Assuming that the motor is operating at relative high speed and that itis desired to bring it to rest, the controller 5 is thrown tosuccessively occupy positions a, y and z, and the reversing switch isthrown to the position 0.

- In position at of the controller 5. the circuit connections correspondto those established in position f except that the field magnet windings2 and 3 are connected in multiple relation and are reversed, thearmature 1 is connected across the entire batteries in series, theresistor 39 is included in the armature circuit, and a resistor 56 isincluded in series with the field branch of the circuit. By this means.a regenerative circuit is established which tends to charge the battery7 and the battery 6, in addition to retarding the speed of the motor. Asthe speed of the motor is reduced, the controller may be moved intoposition 1 in which the resistor 39 is short circuited, and finally intoposition .2 in which both the resistors 3 and 56 are short circuited.

From the above description and the drawings, it will be readilyunderstood that, under the most usual motor operating conditions, thatis, when the controller 5 occupies its position f and the motor isrunning at its highest speed, the portion of the battery 6 is dischargedat a slower rate than the remainder thereof and the battery 7. On theother hand, when the motor is operating regeneratively, the portion ofthe battery 6 is charged at a slower rate than the remainder thereof andthe battery 7. because the said portion 55 is connected in parallel tothe motor field magnet windings. The arrangement is such that theportion 55 will discharge and charge at such a rate as to maintain itscondition of charge substantiallv the same as that of the remainingcells of the batteries. Since the portion 55 is connected parallel withthe motor field magnet windings for regenerative operation,

it serves to determine, to a certain degree,

the drop of potential across the field magnet windings, with the resultthat, under regenerative operating conditions, the field strength or themotor is maintained substantially uniform, except when varied by changeof resistance.

Instead of connecting the field magnet windings 2 and 3 in seriesrelation in position f of the controller, as shown in Fig. '7, they maybe connected in multiple circuit relation and a suitable resistanceincluded in series with them, and, on the contrary, the field magnetwindings may be connected in series relation in the regenerative brakingpositions 50, g and e, or the series relation may be utilized in some ofthe regenerative positions and the multiple circuit relation in others.

Referring to Figs. 11 to 17, of the drawings, in which correspondingparts are designated by the same reference characters, the controllerhere shown difi'ers from that of the previous figures in that a seriesconnection is always maintained between the cells of the storagebattery, the armature resistor being included in the firstmotoroperating position, partially excluded in the second, and whollyshort-circuited in the third. In the fourth motor-operating position,the field magnet windings 2 and 3 are changed from a series to amultiple circuit relation.

\Vhen the controller occupies its dynamic braking positionw the fieldmagnet windings are, of course, reversed, the motor armature isconnected across the entire storage battery and the field magnetwindings are connected in series relation across a portion of thestorage battery.

In the position 1 the field magnet windings are changed from a series toa multiple circuit relation.

Other braking positions may, of course, be established by inserting inthe first position suitable resistance in the armature and fieldcircuits and afterward excluding the same.

Variations in the circuit connections and the arrangements of thecontrol positions may be effected within the spirit and scope of myinvention, and I desire that only such limitations shall be imposed asare indicated in the appended claims.

I claim as my invention:

1. The method of operating an electric motor regeneratively whichconsists in c0nnecting the motor field magnet windings and a port-ion ofthe battery in parallel with each other and in series with the motorarmature and the remainder of the battery.

2. The method of controlling an electric motor which consists, for motoroperation,

in connecting the armature and field magnet windings thereof in serieswith each other and with a battery, and an intermediate point of thebattery to the connection between the armature and field magnetwindings, and, for regenerative operation, in connecting the motor fieldmagnet windings and a portion oi the battery in parallel with each otherand in series with the motor armature and the remainder of the battery.

3. The method of controlling an electric motor that is supplied withenergy from a storage battery which consists in connecting the armatureand field magnet windings in series relation across the storage batteryand interc-onnectin a point between the arrna ture and field magnetwindings and an in termediate point in the battery for relativelyhigh-speed operation.

ii. The method of controlling an electric motor that is supplied withenergy from a storage battery which consists in connecting storagebattery cells in multiple groups and the armature and field magnetwindings of the motor in series relation across the terminals of saidgroups for low-speed operation and connecting the storage battery cellsin series relation and establishing a cross connection frombetween thearmature and. field magnet windings to an intermediate point in thestorage battery for high-speed operation.

5. The method of controlling an electric motor that is supplied withenergy from a storage battery which consists in connecting storagebattery sections in multiple relation, the field magnet winding sectionsin series relation and in series with the motor armature for low-speedoperation, connecting the storage battery sections in series relationfor an intermediate operating speed and estab lishing cross connectionfrom between the armature and field magnet windings to an intermediatepoint in the storage battery "for high-speed operation.

6. The method of controlling an electric motor that is supplied withenergy from a storage battery which consists in the following steps:first, connecting a storage battery in parallel sections, the fieldmagnet winding in series sections and in series relation with the motorarmature; second, connecting the field magnet winding in parallelsections; third, connecting the storage battery in series sections andthe field magnet windings in series sections; fourth, connecting thefield magnet windings in parallel sections, and fifth, establishing across con nection for high-speed operation from between the armature andfield magnet windings to an intermediate point in the storage battery.

7. The method of controlling an electric motor that is supplied withenergy from a. storage battery which consists in connecting the armatureand field magnet windings of the motor in series relation across thebattery for low-speed operation, and establishing an armature circuitindependent of the field magnet windings and embracing a portion of thestorage battery for high-speed operation.

8. The method of controlling an electric motor that is supplied withenergy from a storage battery which consists in connecting the armatureand field magnet windings of the motor in series relation across thebattery for low-speed operation, establishing an armature circuitindependent of the field magnet windings and embracing a portion of thestorage battery for high-speed opera tion and maintaining the high-speedconnection with the field magnet winding reversed for regenerativebraking.

9. The method of controlling a dynamoelectric machine having electricalrelations with a source of energy, which consists in connecting themachine field windings and a portion of said source of energy inparallel with each other and in series with the machine armature andremaining portion of said source of energy.

10. The method of controlling a dynamoelectric machine having electricalrelations with asource of energy, which consists in connecting in seriescircuit relation, the machine armature, a portion of the source ofenergy, and a divided circuit including the remaining portion of saidsource and the machine field windings.

11. The method of operating an electric motor from a battery whichconsists in connecting the motor field windings and portion of saidbattery in multiple and in series with the motor armature and remainingbattery portion.

12. The method of controlling an electric motor during motor operationand regeneration which consists in connecting the motor field windingsand a portion of a battery in multiple with each other and in serieswith another portion of the battery and the motor armature.

13. The method of operating an electric motor from a battery whichconsists in discharging energy at different rates from differentportions of said battery respectively to the motor field windings andthe motor armature during motor operation, and chargingsaid portions ofsaid battery at the same relative rates from said motor duringregeneration.

H. The method of operating an electric motor which consists inconnecting the motor armature in series with a portion of said batteryand the motor field windings in multiple to the remaining portion ofsaid battery during both motor operation and regeneration, whereby therelative rates of charge and discharge of the different battery portionsare substantially maintained.

15. The method of operating an electric motor from a battery whichconsists in connecting the armature and field windings of the motor inseries relation across the battery for low-speed operation and inconnecting the armature and field windings respectively across differentportions of the battery for high speed operation.

16. In av control system, the combination with an electric motor havingan armature and field windings and a storage battery, of a switchingdevice for connecting the field windings and a portion of said batteryin multiple to each other and in series with the remaining portion ofsaid battery and the motor armature.

17. In a control system, the combination with a motor having fieldwindings and an armature and a storage battery, of acontroller adaptedto govern the operation of said motor during acceleration andretardation and to connect the motor armature and the motor fieldwindings respectively across different portions of said battery duringboth operations.

. 1S.'The method of controlling a dynamo-.

electric machine which consists in connecting the armature and fieldmagnet windings of said machine in separate circuits across differentportions of a storage battery during motor operation, and maintainingsaid connections and reversing said field magnet windings duringregenerative braking.

19. The method of operating a dynamoelectric machine from a storagebattery, which consists in connecting the armature and field magnetwindings across different portions of said battery during motoroperation whereby said portions of the battery are discharged atdifferent rates, and maintaining the same circuit connections with thefield magnet windings reversed during regeneration, whereby saidportions of the battery are charged at the same relative rates that theyare discharged.

20. The method of operating a dynamoelectric machine from a storagebattery, which consists in connecting the armature and field-magnetwindings in series circuit with the whole of the storage battery forlow-speed operation, and in separate multiple circuits across differentportions of said battery for high-speed operation, whereby the whole ofsaid battery is discharged at the same rate at low speed and thedifferent portions discharged at relatively different rates at highspeed, and in maintaining the high-speed connections with reversedfield-magnet windings during regeneration, whereby the dif'l'erentportions of the battery are charged at substantially the same relativerates that they are subscribed my naine this fourth lay of discharged athigh-speed operation, in such October, 1912.

manner that the several battery portions NORMAN W. STORER. aremaintained in a substantially uniform itnesses: 5 state of charge ordischarge. 0. BIELER,

In testimony whereof, I have hereunto B. B. HINES.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

' Washington, D. C.

